Lower Foundation Box

I made some progress over the past few days. Here you can see the sub-grade insulated box within corner post and sill cap. The posts are 2"x6" p.t. lumber, 32" tall screwed together in an L shape. The sill is made of 2x4 p.t. lumber over posts. 1x5 p.t. lumber is screwed/glued to the outside of the sill to act as an attachment point for posts and frame to be built above.